1. Field of the Invention
The present invention relates to novel spiro-3-heteroazolidine compounds and salts thereof, a process for the preparation of the compounds as well as a pharmaceutical agent comprising at least one of the compounds to cure or prevent a complication due to diabetes.
2. Related Arts
Hithereto, various studies have been made for an effective agent for curing diabetes, which can be orally dosed. As a result, various agents therefor, each of which comprises as an effective component, sulfonyl urea, mesooxalate or guanidine derivative or the like, have been developed and marketed, but those are of a mere symptomatic treating agent to a hypergloycoplasmia due to the diabetes. It has been known there may be caused due to the diabetes specific chronic complications such as diabetic cataract, diabetic neuropathy, diabetic retinopathy and the like but there is almost no effective agent for curing the complications and thus it may be said that no effective therapeutic system has been established.
Therefore, hithereto, various studies have also been made for developing an effective agent for curing such intractable deseases due to the diabetes but it is the fact that there are almost no success cases. As one of the studies, there is a search on inhibition substance to aldose reductase enzymes, since the enzyme reduces in vivo of human and other animals, aldoses such as glucose and galactose into corresponding polyols such as sorbitol and galactitol and it has been known that said complications will appear when the formed sorbitol and galactitol are accumulated at crystalline lens, peripheral nerve, kidney or the like in patients with diabetes or galactosemia ["Jap. J. Opthalmol." Vol. 20, page 399 (1976); "Int. Congr. Ser. Excerpta Med." Vol. 403, page 594 (1977); and "Metabolism" Vol. 28, page 456 (1979)].